Drum of disc bowl centrifuge for separating liquid mixture



DRUM or" DISC BOWL CENITRIFUGEFOR'SEPARATINGLIQUID MIXTURE Filed July14, 1965 United States Patent Ofiice 3,371,859 Patented Mar. 5, 19683,371,859 DRUM F DISQ BOWL CENTRIFUGE FOR SEPARATING LlQUlllD MIXTUREIvan Vasilievich lLyskovtsov, Varshavslroe Chaussee, 180, Ker-pus 2,lrv. 30, Moscow, U.S.S.R. Filed July 14, 1965, Ser. No. 471,935 1 Claim.(Cl. 23320) ABSTRACT OF THE DISCLQSURE A drum for a disc bowl centrifugefor separating liquid mixtures containing non-fluid fractions, includinga body, a holder provided with discs mounted in the body, a workingchamber constituted by the spaces between the discs, a reservoir foraccumulating the non-fluid fraction arranged behind and concentricallywith respect to the working chamber, discharge slots in the body servingto discharge the non-fiuid fraction from the reservoir due tocentrifugal forces, a first piston within the body for closing andopening the discharge slots, a second piston operably related to thefirst piston and body for cuttingoff a portion of the reservoir and saidsecond and first pistons alternately moving along the axis of the drumfor bringing the cut-off portion of the reservoir into communicationwith the working chamber and with a receiver for the non-fluid fractionlocated exteriorly of the drum via the discharge slots.

The present invention relates to disc bowl centrifuges for separatingliquid mixtures, and more particularly to the drums of disc bowlcentrifuges used for separating liquid mixtures containing non-fluidfractions.

The drums of disc bowl centrifuges known heretofore and used to separateliquid mixtures containing nonfiuid fractions comprise a working chamberdefined by the discs, a reservoir for the accumulation of the nonfluidfraction arranged concentrically behind the working chamber, and apiston serving to overlap the discharge slots of the drum during theprocess of separation.

These centrifuges allow not only a manual discharge of the non-fluidfraction but also an automatic discharge under the action of centrifugalforces. During the discharge of the non-fluid fraction, however, theprocess of separation is discontinued since in the course of discharge ahermetic sealing of the working chamber cannot be effected.

It is therefore an object of the present invention to provide a drum forthe disc bowl centrifuge for the separation of liquid mixturescontaining non-fluid fractions which will permit an automatic dischargeof the non-fluid fraction in the course of a continuous separationprocess.

Another object of the invention is to provide a drum for the disc bowlcentrifuge for separating liquid mixtures containing non-fluid fractionsin which a hermetic sealing of the working chamber is ensured during theperiod of discharging the non-fluid fraction from the drum.

Yet another object of the present invention is to provide a drum for thedisc bowl centrifuge for separating liquid mixtures containing non-fluidfractions in which the non-fluid fraction being discharged will containa aninimum percentage of moisture.

In accordance with the above and other objects, the present drum for usein a disc bowl centrifuge for separating liquid mixtures containingnon-fluid fractions comprises a working chamber formed in the spacesbetween the discs, a reservoir for the accumulation of the nonfiuidfraction arranged concentrically behind the working chamber, and a firstpiston serving to overlap the discharge slots of the drum in the processof separation, the piston being provided with a second piston disposedin said dmm and adapted to cut off a portion of the reservoir for theaccumulation of the non-fluid fraction during the discharge period ofsaid fraction from the cut-off portion of the reservoir into a receiveroutside of the drum.

The second piston travels alternately with the first piston whichoverlaps the discharge slots of the drum thus connecting the cut-offportion of the reservoir with the working chamber and with the receiveroutside the drum, respectively.

The present invention thus makes it possible to efl ect an automaticdischarge of the non-fluid fraction in the course of a continuousprocess of separation, while the hermetic sealing of the working chamberduring the discharge provides for a minimum percentage of moisture inthe non-fluid fraction being discharged.

The invention is further described in accordance with one particularembodiment thereof given by way of illustration with due reference tothe a-ccompaying drawing in which the drum of the disc bowl centrifugeis shown in axial section.

The drum of the invention comprises a body 1 in which a holder 2provided with discs 3 is disposed. The spaces between the discsconstitute a working chamber behind which and concentrically arrangedtherewith is a reservoir for the accumulation of the non-fiuid fraction.A portion of the reservoir is defined by a cover 4 and a disc 5.

To overlap or open and close discharge slots a of the body 1 a firstpiston 6 movable along the axis of the drum is provided. The cut-off ofa portion of the reservoir for accumulating the non-fluid fractionduring the period of discharge of the fraction is effected by means of asecond piston 7 also movable along the axis of the drum. All of theelements of the drum disposed in the body 1 are fixed in position bymeans of a nut 8 threadedly engaging the side wall of the body.

In the upper portion of the drum head disc 10 provided with a feedingtube 9 is positioned and the disc is formed with channels b throughwhich the clarified liquid fraction is drained from the working chamberof the drum.

The drum is fixed on the upper end of a vertical shaft 12 of thecentrifuge by means of a nut 11 and rotates together with the shaft.

The joints between the elements of the drum are sealed with gaskets.

The operation of the invention is as follows:

Auxiliary fluid (water) is fed or introduced through ducts d and slits einto space c of the drum located below the piston 6 and the bottom wallof the body 1 and any excess fluid overflows through opening 1 providedin the bottom wall. When the fluid feed is stopped, its residue willflow from upper space g located between pistons 6 and 7 through openingsh and i to the outside of the body, and the auxiliary fluid stillcontained in space 0, by pressing on the lower surface of the piston 6,will urge the piston upwards until the piston bears against a packingring 13. The piston 6 will then overlap or close the discharge slots aof the body, whereby the working chamber of the drum and the reservoirfor the accumulation of the non-fluid fraction are hermetically sealedor isolated from the receiver outside the drum.

Then, the liquid mixture containing a non-fluid fraction is fed via ductj for separation. This mixture by exerting pressure on the conicalsurface of piston 7 will urge the piston 7 downwards and thus bring thecut-off portion of the reservoir serving to accumulate the non-fluidfraction into communication with the working chamber of the drum.

Under the action of centripetal forces, solid particles which areheavier than the dispersion medium, are separated and accumulate in thereservoir for the non-fluid fraction.

As soon as a portion of the reservoir in the drum is filled withseparated particles forming the non-fluid fraction, auxiliary fluid isfed through duct d into space g. The excess of the fluid escapes throughopenings h and f and slits 2.

When the auxiliary fluid partially fills the space g, the pressurealfecting the lower surface of the piston 7 becomes greater than that ofthe liquid mixture above the piston. The piston 7 will be urged upwardsuntil it bears against a packing ring 14, thus cutting off a portion ofthe reservoir for the non-fluid fraction from the working chamber.

When the space g is completely filled with the auxiliary fluid, thepressure thus built up and acting on the surface of the piston 6 will begreater than the pressure acting on the bottom of the piston 6 andcreated by the auxiliary fluid in the space 0 which has a free surfaceon the radius (with respect to the axis of the drum) where the opening fis located. As soon as the piston 6 has travelled downwards, thenon-fluid fraction from the cut-off portion of the reservoir will bedischarged into the receiver outside the drum through the slots a of thebody 1 under the action of centrifugal forces. Thereafter, the feed ofthe auxiliary fluid into space g is discontinued. The residue of theauxiliary fluid will escape from such space through openings h and i.When part of the fluid leaves the space g, the piston 6 will firsttravel upwards, with the pressure force of the auxiliary fluid frombelow being greater, and then, when the amount of auxiliary fluid in thespace g becomes insignificant, the pressure exerted by the fluid mixtureon the piston 7 from above will urge the latter downwards.

As a consequence, the working chamber will be placed into communicationwith the cut-ofl portion of the reservoir for the non-fluid fractionwhere separated particles will again accumulate thus forming thenon-fluid fraction.

Such alternate travel of the pistons 6 and 7 enables the cut-off portionof the reservoir for the non-fluid fraction to be placed in turn incommunication with the working chamber and with the receiver outside thedrum.

Hence it is possible to eflect an automatic discharge of the non-fluidfraction of any physico-chemical structure from the drum with a minimumpercentage of moisture and without interrupting the process ofseparation for the period of such discharge, i.e. to effect a continuousprocess of separation of liquid mixtures containing nonfluid fractions.

The invention is not to be confined to any strict conformity to theshowings in the drawings but changes or modifications may be madetherein so long as such changes or modifications mark no materialdeparture from the spirit and scope of the appended claims.

What is claimed is:

1. A drum for a disc bowl centrifuge for separating liquid mixturescontaining non-fluid fractions, comprising a body having a bottom wall,a side wall and an open end, a holder disposed within said body, discsarranged on said holder, a working chamber defined by the spaces betweensaid discs, means providing a reservoir for accumulating the non-fluidfraction behind and concentrically arranged respecting said workingchamber, said reservoir providing means including a cover for said openend of said body and a disc located between said cover and said bottomwall, said side wall having discharge slots communicating with saidreservoir for discharging the non-fluid fraction due to centrifugalforce, a first piston mounted within said body for axial movementbetween the bottom wall and the cover whereby movement towards the covercloses the discharge slots and movement towards the bottom wall opensthe discharge slots, a second piston mounted within the first piston foraxial movement between the head of the first piston and said cover forcuttingotf a portion of said reservoir, means for introducing anauxiliary fluid into a space between the bottom wall of the body and thefirst piston for moving said piston axially until it engages said coverthereby closing said discharge slots and sealing said working chamberand reservoir from the outside of said body, and means for introducing aliquid mixture containing a non-fluid fraction into the working chamberwhereby said mixture moves said second piston toward the head of thefirst piston for providing communication between the working chamber andcut-off portion of the reservoir with the non-fluid fractions beingseparated and accumulated in the reservoir due to centripetal forces,the fluid being fed into the space between the second piston and thehead of the first piston and when the pressure in such space exceedsthat of the liquid mixture, the second piston moves axially until itengages the cover thus isolating the reservoir from the working chamberand when such latter space is filled with fluid, the first piston movestoward the bottom wall opening the discharge slots so that the non-fluidfraction in the cut-ofl portion of the reservoir will be dischargedtherethrough into a receiver located outside said body.

References Cited UNITED STATES PATENTS 3,193,194 7/1965 Steinacker 233-20 FOREIGN PATENTS 625,067 2/ 1936 Germany.

HENRY T. KLINKIEK, Primary Examiner.

